The principal objective of the research is to study hormonal influences on collagen and elastin cross-links in affecting the tensile properties of vascular tissue. The ultimate aim is to understand the basis for sex differences in vascular aging and in focal atherogenesis in man. Hormonal influences on collagen cross-linking during maturation will be investigated in the Ivalon capsule-tissue from adult rats. In this model system, the temporal changes in the profile of (3H)NaBH4-reducible lysyl-derived cross-links as collagen matures into well-ordered bundles are now known. Questions regarding sex differences in the cross-linking profile and in collagen types, in vivo reduction or a catabolism of borohydride-reducible cross-links or that formation of borohydride-nonreducible cross-links during collagen maturation can be answered with the Ivalon-implant system. Chemical characterization of borohydride-nonreducible cross-links will include analysis by NMR and mass spectroscopy. Location of the cross-links formed during collagen maturation along the collagen molecule will be studied by isolating the chain-linking cyanogen bromide peptides of collagen and determining their amino acid composition and sequence. The possibility of hormone mediation of collagen cross-link formation via modifying tissues levels of biogenic amines (serotonin, catecholamine and histamine) will be investigated in the Ivalon-implant system and by an in vitro system of intermolecular collagen cross-link formation of soluble collagen. Finally, the mechanism(s) of hormonal action on collagen and elastin cross-link formation in the abdominal aorta of the Broad Breasted White (BBW) turkey will be studied in the intact animal and in abdominal aorta organ culture.